Active transport 4.4

What is active transport?

The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins

How does it differ from passive forms of transport ?

-metabolic energy is needed in the form of ATP
Substrates moved against a concentration gradient
Carrier proteins are involved
The process is very selective

What is the process? (7)

1)- the carrier proteins span the plasma membrane and bind to the molecule that needs to be transported to the other side

2)- the molecule binds to the receptor sites on the carrier proteins

3)- one the inside of the cell atp binds to the protein and it is hydrolysed into adp and a phosphate molecule

4)As a result the protein changes shape and opens to the opposite site of the membrane

5)The molecule is then released to the other side of the membrane

6)The phosphate molecule is released from thr protein which causes the protein to revert to its original shape ,ready to repeat the process

7)The phosphate molecule is released then recombines with the adp to form atp during respiration

What happens when more than one molecule is moved in the same direction at the same time by active transport ?

The molecule or ion is being moved into a cell at the same time a different one is bring removed
E.g sodium potassium pump

What happens in the sodium potassium pump ?

Sodium ions are actively removed from the cell while potassium ions are actively taken in the from the surroundings .this process is essential to a number of important process in the organism